/in/foo.cc: In function 'int main()':
/in/foo.cc:12:14: error: 'opt' was not declared in this scope
         cin>>opt>>l>>r>>c;
              ^~~
/in/foo.cc:12:19: error: 'l' was not declared in this scope
         cin>>opt>>l>>r>>c;
                   ^
/in/foo.cc:12:22: error: 'r' was not declared in this scope
         cin>>opt>>l>>r>>c;
                      ^
/in/foo.cc:12:25: error: 'c' was not declared in this scope
         cin>>opt>>l>>r>>c;
                         ^